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Nutrition in Infants

by Deborah M. Consolini, MD

If the delivery was uncomplicated and the neonate is alert and healthy, the neonate can be brought to the mother for feeding immediately. Successful breastfeeding is enhanced by putting the neonate to the breast as soon as possible after delivery. Spitting mucus after feeding is common (because gastroesophageal smooth muscle is lax) but should subside within 48 h. If spitting mucus or emesis persists past 48 h or if vomit is bilious, complete evaluation of the upper GI and respiratory tracts is needed to detect congenital GI anomalies (see Congenital Gastrointestinal Anomalies).

Daily fluid and calorie requirements vary with age and are proportionately greater in neonates and infants than in older children and adults ( Calorie Requirements at Different Ages*). Relative requirements for protein and energy (g or kcal/kg body weight) decline progressively from the end of infancy through adolescence ( Recommended Dietary Reference Intakes* for Some Macronutrients, Food and Nutrition Board, Institute of Medicine of the National Academies), but absolute requirements increase. For example, protein requirements decrease from 1.2 g/kg/day at 1 yr to 0.9 g/kg/day at 18 yr, and mean relative energy requirements decrease from 100 kcal/kg at 1 yr to 40 kcal/kg in late adolescence. Nutritional recommendations are generally not evidence-based. Requirements for vitamins depend on the source of nutrition (eg, breast milk vs standard infant formula), maternal dietary factors, and daily intake.

Calorie Requirements at Different Ages*





< 6 mo



1 yr



15 yr



*When protein and calories are provided by breast milk that is completely digested and absorbed, the requirements between 3 mo and 9 mo of age may be lower.

Feeding problems

Minor variations in day-to-day food intake are common and, although often of concern to parents, usually require only reassurance and guidance unless there are signs of disease or changes in growth parameters, particularly weight (changes in the child’s percentile rank on standard growth curves are more significant than absolute changes).

Loss of > 5 to 7% of birth weight in the first week indicates undernutrition. Birth weight should be regained by 2 wk, and a subsequent gain of about 20 to 30 g/day (1 oz/day) is expected for the first few months. Infants should double their birth weight by about 6 mo.


Breast milk is the nutrition of choice. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for a minimum of 6 mo and introduction of appropriate solid food from 6 mo to 1 yr. Beyond 1 yr, breastfeeding continues for as long as both infant and mother desire, although after 1 yr breastfeeding should complement a full diet of solid foods and fluids. To encourage breastfeeding, practitioners should begin discussions prenatally, mentioning the multiple advantages:

  • For the child: Nutritional and cognitive advantages and protection against infection, allergies, obesity, Crohn disease, and diabetes

  • For the mother: Reduced fertility during lactation, more rapid return to normal prepartum condition (eg, uterine involution, weight loss), and protection against osteoporosis, obesity, and ovarian and premenopausal breast cancers

Milk production is fully established in primiparas by 72 to 96 h and in less time in multiparas. The first milk produced is colostrum, a high-calorie, high-protein, thin yellow fluid that is immunoprotective because it is rich in antibodies, lymphocytes, and macrophages; colostrum also stimulates passage of meconium. Subsequent breast milk has the following characteristics:

  • Has a high lactose content, providing a readily available energy source compatible with neonatal enzymes

  • Contains large amounts of vitamin E, an important antioxidant that may help prevent anemia by increasing erythrocyte life span

  • Has a Ca:P ratio of 2:1, which prevents Ca-deficiency tetany

  • Favorably changes the pH of stools and the intestinal flora, thus protecting against bacterial diarrhea

  • Transfers protective antibodies from mother to infant

  • Contains cholesterol and taurine, which are important to brain growth, regardless of the mother’s diet

  • Is a natural source of ω-3 and ω-6 fatty acids

These fatty acids and their very long-chain polyunsaturated derivatives (LC-PUFAS), arachidonic acid (ARA) and docosahexaenoic acid (DHA), are believed to contribute to the enhanced visual and cognitive outcomes of breastfed compared with formula-fed infants. Most commercial formulas are now supplemented with ARA and DHA to more closely resemble breast milk and to reduce these potential developmental differences.

If the mother’s diet is sufficiently diverse, no dietary or vitamin supplementation is needed for the mother or her term breastfed infant. However, to prevent vitamin D deficiency rickets, vitamin D 200 units once/day beginning in the first 2 mo is given to all infants who are exclusively breastfed. Premature and dark-skinned infants and infants with limited sunlight exposure (residence in northern climates) are especially at risk of vitamin D deficiency. After 6 mo, breastfed infants in homes where the water does not have adequate fluoride (supplemental or natural) should be given fluoride drops. Clinicians can obtain information about fluoride content from a local dentist or health department.

Infants < 6 mo should not be given additional water because hyponatremia is a risk.

Breastfeeding Technique

The mother should use whatever comfortable, relaxed position works best and should support her breast with her hand to ensure that it is centered in the infant’s mouth, minimizing any soreness. The center of the infant’s lower lip should be stimulated with the nipple so that rooting occurs and the mouth opens wide. The infant should be encouraged to take in as much of the breast and areola as possible, placing the lips 2.5 to 4 cm from the base of the nipple. The infant’s tongue then compresses the nipple against the hard palate. Initially, it takes at least 2 min for the let-down reflex to occur. Volume of milk increases as the infant grows and stimulation from suckling increases. Feeding duration is usually determined by the infant. Some mothers require a breast pump to increase or maintain milk production; in most mothers, a total of 90 min/day of breast pumping divided into 6 to 8 sessions produces enough milk for an infant who is not directly breastfed.

The infant should nurse on one breast until the breast softens and suckling slows or stops. The mother can then break suction with a finger before removing the infant from one breast and offering the infant the second. In the first days after birth, infants may nurse on only one side; then the mother should alternate sides with each feeding. If the infant tends to fall asleep before adequately nursing, the mother can remove the infant when suckling slows, burp the infant, and move the infant to the other side. This switch keeps the infant awake for feedings and stimulates milk production in both breasts.

Mothers should be encouraged to feed on demand or about every 1½ to 3 h (8 to 12 feedings/day), a frequency that gradually decreases over time; some neonates < 2500 g may need to feed even more frequently to prevent hypoglycemia. In the first few days, neonates may need to be wakened and stimulated; small infants and late preterm infants should not be allowed to sleep long periods at night. Large full-term infants who are feeding well (as evidenced by stooling pattern) can sleep longer. Eventually, a schedule that allows infants to sleep as long as possible at night is usually best for the infant and family.

Mothers who work outside the home can pump breast milk to maintain milk production while they are separated from their infants. Frequency varies but should approximate the infant’s feeding schedule. Pumped breast milk should be immediately refrigerated if it is to be used within 48 h and immediately frozen if it is to be used after 48 h. Refrigerated milk that is not used within 96 h should be discarded because risk of bacterial contamination is high. Frozen milk should be thawed by placing it in warm water; microwaving is not recommended.

Infant Complications

The primary complication is underfeeding, which may lead to dehydration and hyperbilirubinemia (see Neonatal Hyperbilirubinemia). Risk factors for underfeeding include small or premature infants and mothers who are primiparous, who become ill, or who have had difficult or operative deliveries. A rough assessment of feeding adequacy can be made by daily diaper counts. By age 5 days, a normal neonate wets at least 6 diapers/day and soils at least 4 diapers/day; lower numbers suggest underhydration and undernutrition. Also, stools should have changed from dark meconium at birth to light brown and then yellow. Weight is also a reasonable parameter to follow (see Care of Newborns and Infants:Feeding problems); not attaining growth landmarks suggests undernutrition. Constant fussiness before age 6 wk (when colic may develop unrelated to hunger or thirst) may also indicate underfeeding. Dehydration should be suspected if vigor of the infant’s cry decreases or skin becomes turgid; lethargy and sleepiness are extreme signs of dehydration and should prompt testing for hypernatremia.

Maternal Complications

Common maternal complications include breast engorgement, sore nipples, plugged ducts, mastitis, and anxiety.

Breast engorgement, which occurs during early lactation and may last 24 to 48 h, may be minimized by early frequent feeding. A comfortable nursing brassiere worn 24 h/day can help, as can applying cool compresses after breastfeeding and taking a mild analgesic (eg, ibuprofen). Just before breastfeeding, mothers may have to use massage and warm compresses and express breast milk manually to allow infants to get the swollen areola into their mouth. Excessive expression of milk between feedings facilitates engorgement, so expression should be done only enough to relieve discomfort.

For sore nipples, the infant’s position should be checked; sometimes the infant draws in a lip and sucks it, which irritates the nipple. The mother can ease the lip out with her thumb. After feedings, she can express a little milk, letting the milk dry on the nipples. After breastfeeding, cool compresses reduce engorgement and provide further relief.

Plugged ducts manifest as mildly tender lumps in the breasts of lactating women who have no other systemic signs of illness. Continued breastfeeding ensures adequate emptying of the breast. Warm compresses and massage of the affected area before breastfeeding may further aid emptying. Women may also alternate positions because different areas of the breast empty better depending on the infant’s position at the breast. A good nursing brassiere is helpful because regular brassieres with wire stays or constricting straps may contribute to milk stasis in a compressed area.

Mastitis is common and manifests as a tender, warm, swollen, wedge-shaped area of breast. It is caused by engorgement, blocking, or plugging of an area of the breast; infection may occur secondarily, most often with penicillin-resistant Staphylococcus aureus and less commonly with Streptococcus sp or Escherichia coli. With infection, fever 38.5° C, chills, and flu-like aching may develop. Diagnosis is by history and examination. Cell counts (WBCs > 10 6 /mL) and cultures of breast milk (bacteria >10 3 /mL) may distinguish infectious from noninfectious mastitis. If symptoms are mild and present <24 h, conservative management (milk removal via breastfeeding or pumping, compresses, analgesics, a supportive brassiere, and stress reduction) may be sufficient. If symptoms do not lessen in 12 to 24 h or if the woman is acutely ill, antibiotics that are safe for breastfeeding infants and effective against S. aureus (eg, dicloxacillin, cloxacillin, or cephalexin 500 mg po qid) should be started; duration of treatment is 10 to 14 days. Community-acquired methicillin-resistant S. aureus should be considered if cases do not respond promptly to these measures or if an abscess is present. Complications of delayed treatment are recurrence and abscess formation. Breastfeeding may continue during treatment.

Maternal anxiety, frustration, and feelings of inadequacy may result from lack of experience with breastfeeding, mechanical difficulties holding the infant and getting the infant to latch on and suck, fatigue, difficulty assessing whether nourishment is adequate, and postpartum physiologic changes. These factors and emotions are the most common reasons mothers stop breastfeeding. Early follow-up with a pediatrician or consultation with a lactation specialist is helpful and effective for preventing early breastfeeding termination.


Breastfeeding mothers should avoid taking drugs if possible. When drug therapy is necessary, the mother should avoid contraindicated drugs and drugs that suppress lactation (eg, bromocriptine, levodopa, trazodone). The US National Library of Medicine maintains an extensive database regarding drugs and breastfeeding at the Drugs and Lactation Database , which should be consulted regarding use of or exposure to specific drugs or classes of drugs. For some common drugs contraindicated for breastfeeding mothers, Some Drugs Contraindicated for Breastfeeding Mothers.

When drug treatment is necessary, the safest known alternative should be used; when possible, most drugs should be taken immediately after breastfeeding or before the infant’s longest sleep period, although this strategy is less helpful with neonates who nurse frequently and exclusively. Knowledge of the adverse effects of most drugs comes from case reports and small studies. Safety of some drugs (eg, acetaminophen, ibuprofen, cephalosporins, insulin) has been determined by extensive research, but others are considered safe only because there are no case reports of adverse effects. Drugs with a long history of use are generally safer than newer drugs for which few data exist.

Some Drugs Contraindicated for Breastfeeding Mothers

Drug Class


General Concerns and Specific Effects in Infants




May be given cautiously but, in very large doses, may cause hemorrhage (heparin is not excreted in milk)

Cytotoxic drugs





May interfere with cellular metabolism of a breastfeeding infant, causing possible immunosuppression and neutropenia

Unknown effect on growth and unknown association with carcinogenesis

Psychoactive drugs

Anxiolytics, including benzodiazepines (alprazolam, diazepam, lorazepam, midazolam, prazepam, quazepam, temazepam) and perphenazine

Antidepressants (tricyclics, SSRIs, bupropion)

Antipsychotics (chlorpromazine, chlorprothixene, clozapine, haloperidol, mesoridazine, trifluoperazine)

For most psychoactive drugs, unknown effect on infants, but because drugs and metabolites appear in breast milk and in infant plasma and tissues, possible alteration of short-term and long-term CNS function

Fluoxetine: Linked to colic, irritability, feeding and sleep disorders, and slow weight gain

Chlorpromazine: Possible drowsiness, lethargy, decline in developmental scores

Haloperidol: Decline in developmental scores

Individual drugs that are detectable in breast milk and pose theoretical risk


Possible hypothyroidism


Possible idiosyncratic bone marrow suppression


Potential for transfer of high percentage of maternal dose

Possible increase in skin pigmentation


With large maternal doses given for weeks or months, can produce high concentrations in milk and may suppress growth and interfere with endogenous corticosteroid production in the infant


Potential for therapeutic serum concentrations in the infant


None described



In vitro mutagens

May stop breastfeeding for 12–24 h to allow excretion of dose when a mother is given a single dose of 2 g

Safe after the infant is 6 mo



Caution required if infants have jaundice or G6PD deficiency or are ill, stressed, or premature

Individual drugs that are detectable in breast milk and have documented risk


Hypotension, bradycardia, tachypnea

Aminosalicylic acid



Cyanosis, bradycardia


Suppresses lactation

May be hazardous to the mother

Aspirin (salicylates)

Metabolic acidosis

With large maternal doses and sustained use, may produce plasma concentrations that increase risk of hyperbilirubinemia (salicylates compete for albumin-binding sites) and hemolysis only in G6PD-deficient infants that are < 1 mo


Drowsiness, irritability, refusal to feed, high-pitched cry, neck stiffness


Vomiting, diarrhea, seizures (with doses used in migraine drugs)


Withdrawal vaginal bleeding





1 / 3 to 1 / 2 therapeutic blood concentration in infants


Sedation, infantile spasms after weaning, methemoglobinemia




Sedation, feeding problems

Sulfasalazine (salicylazosulfapyridine)

Bloody diarrhea

Nitrofurantoin, sulfapyridine, sulfisoxazole

Hemolysis in infants with G6PD deficiency; safe in others

Drugs of abuse*


Irritability, poor sleeping pattern


With < 1 g/kg daily, decreased milk ejection reflex

With large amounts, drowsiness, diaphoresis, deep sleep, weakness, decrease in linear growth, abnormal weight gain in the infant


Cocaine intoxication: Irritability, vomiting, diarrhea, tremulousness, seizures


Tremors, restlessness, vomiting, poor feeding


Components detectable in breast milk but effects uncertain



*Effects of smoking are unclear; nicotine is detectable in breast milk, and smoking decreases breast milk production and infant weight gain but may decrease incidence of respiratory illness.

Data from Committee on Drugs of the American Pediatric Association: The transfer of drugs and other chemicals into human milk. Pediatrics108(3):776–789, 2001.


Weaning can occur whenever the mother and infant mutually desire, although preferably not until the infant is at least 12 mo old. Gradual weaning over weeks or months during the time solid food is introduced is most common; some mothers and infants stop abruptly without problems, but others continue breastfeeding 1 or 2 times/day for 18 to 24 mo or longer. There is no correct schedule.

Formula Feeding

The only acceptable alternative to breastfeeding during the first year is formula; water can cause hyponatremia, and whole cow’s milk is not nutritionally complete. Advantages of formula feeding include the ability to quantify the amount of nourishment and the ability of family members to participate in feedings. But all other factors being equal,these advantages are outweighed by the undisputed health benefits of breastfeeding.

Commercial infant formulas are available as powders, concentrated liquids, and prediluted (ready-to-feed) liquids; each contains vitamins, and most are supplemented with iron. Formula should be prepared with fluoridated water; fluoride drops (0.25 mg/day po) should be given after age 6 mo in areas where fluoridated water is unavailable and when using prediluted liquid formula, which is prepared with nonfluoridated water.

Choice of formula is based on infant need. Cow’s milk–based formula is the standard choice unless spitting up, diarrhea (with or without blood), rash (hives), or poor weight gain suggests sensitivity to cow’s milk protein or lactose intolerance (extremely rare in neonates); then, a change in formula may be recommended. All soy formulas in the US are lactose free, but some infants allergic to cow’s milk protein may also be allergic to soy protein; then, a hydrolyzed formula is indicated. Hydrolyzed formulas are derived from cow’s milk, but the proteins are broken down into smaller chains, making them less allergenic. True elemental formulas made from free amino acids are available for the few infants who have allergic reactions to hydrolyzed formula.

Bottle-fed infants are fed on demand, but because formula is digested more slowly than breast milk, they typically can go longer between feedings, initially every 3 to 4 h. Initial volumes of 15 to 60 mL (0.5 to 2 oz) can be increased gradually during the first week of life up to 90 mL (3 oz) about 6 times/day, which supplies about 120 kcal/kg at 1 wk for a 3-kg infant.

Solid Foods

The WHO recommends exclusive breastfeeding for about 6 mo, with introduction of solid foods thereafter. Other organizations suggest introducing solid food between age 4 mo and 6 mo while continuing breastfeeding or bottle-feeding. Before 4 mo, solid food is not needed nutritionally, and the extrusion reflex, in which the tongue pushes out anything placed in the mouth, makes feeding of solids difficult.

Initially, solid foods should be introduced after breastfeeding or bottle-feeding to ensure adequate nourishment. Iron-fortified rice cereal is traditionally the first food introduced because it is nonallergenic, easily digested, and a needed source of iron. It is generally recommended that only one new, single-ingredient food be introduced per week so that food allergies can be identified. Foods need not be introduced in any specific order, although in general they can gradually be introduced by increasingly coarser textures—eg, from rice cereal to soft table food to chopped table food. Meat, pureed to prevent aspiration, is a good source of iron and zinc (both of which can be limited in the diet of an exclusively breastfed infant) and is therefore a good early complementary food. Vegetarian infants can get adequate iron from iron-fortified cereals and grains, green leafy vegetables, and dried beans and adequate zinc from yeast-fermented whole-grain breads and fortified infant cereals.

Home preparations are equivalent to commercial foods, but commercial preparations of carrots, beets, turnips, collard greens, and spinach are preferable before 1 yr if available because they are screened for nitrates. High nitrate levels, which can induce methemoglobinemia in young children, are present when vegetables are grown using water supplies contaminated by fertilizer.

Foods to avoid include

  • Eggs and peanuts usually until children are age 1 yr to prevent food sensitivities

  • Honey until 1 yr because infant botulism is a risk

  • Foods that, if aspirated, could obstruct the child’s airway (eg, nuts, round candies, popcorn, hot dogs, meat unless it is pureed, grapes unless they are cut into small pieces)

Nuts should be avoided until age 2 or 3 because they do not fully dissolve with mastication and small pieces can be aspirated whether bronchial obstruction is present or not, causing pneumonia and other complications.

At or after 1 yr, children can begin drinking whole cow’s milk; reduced-fat milk is avoided until 2 yr, when their diet essentially resembles that of the rest of the family. Parents should be advised to limit milk intake to 16 to 24 oz/day in young children; higher intake can reduce intake of other important sources of nutrition and contribute to iron deficiency.

Juice is a poor source of nutrition, contributes to dental caries, and should be limited to 4 to 6 oz/day or avoided altogether.

By about 1 yr, growth rate usually slows. Children require less food and may refuse it at some meals. Parents should be reassured and advised to assess a child’s intake over a week rather than at a single meal or during a day. Underfeeding of solid food is only a concern when children do not achieve expected weights at an appropriate rate.

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